-LRB- CNN -RRB- -- Unseeded Frenchwoman Aravane Rezai produced one of the shocks of the year on Sunday by defeating favorite Venus Williams in straight sets to win the final of the Madrid Open .

The 23-year-old Rezai -- who had only claimed WTA Tour titles at Strasbourg and Bali prior to Madrid -- continued her remarkable week with a 6-2 7-5 victory , adding Williams ' scalp to her earlier surprise victories over former world number one 's Junstine Henin and Jelena Jankovic .

Williams , who returns to No. 2 in the world behind younger sister Serena on Monday , lost the opening set in just 27 minutes and then failed to take advantage of a 4-1 lead in the second set .

`` I just can not believe this , '' world number 24 Rezai -- who must now enter calculations for the French Open -- told reporters .

`` Venus played very well and I 've always respected her as a player and a champion . I just tried my best today and it worked well for me . ''

Williams , who was looking to secure her 44th career title , only converted two of her 13 break points in the match -- a statistic that contributed greatly to her defeat .

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Unseeded Aravane Rezai claims victory in the Madrid Open final on Sunday

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Rezai secures a stunning straight sets win over favorite Venus Williams

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The success gives the 23-year-old Frenchwoman just the third title of her career